Vacuum IG units are known in the art. For example, see U.S. Pat. Nos. 5,664,395; 5,657,607; 5,897,927; 5,902,652; and 6,261,652, the disclosures of which are all hereby incorporated herein by reference. See also U.S. Pat. No. 6,692,600, the entire contents of which is hereby incorporated herein by reference.
FIGS. 1-2 illustrate a conventional vacuum IG unit. IG unit 1 includes a pair of spaced apart glass substrates 2 and 3 that enclose an evacuated or low pressure space/cavity 6 therebetween. Glass sheets/substrates 2 and 3 are interconnected by peripheral or edge seal 4 of fused solder glass. An array of support pillars or spacers 5 are provided between the substrates in order to space substrates 2, 3 from one another in order to form the space/cavity 6.
In order to evacuate the space/cavity 6, pump out tube 8 is hermetically sealed by solder glass 9 to an aperture or hole 10, which passes from an interior surface of substrate 2 to the bottom of recess 11 formed in the exterior face of substrate 2. A vacuum pump (not shown in FIGS. 1-2) is attached to pump out tube 8, so that the interior cavity 6 between substrates 2 and 3 can be evacuated (i.e., pumped out) to create low pressure in cavity/space 6. Following evacuation, tube 8 may be melted to seal the vacuum. Optionally, a chemical getter 12 may be included within recess 13.
The interior cavity 6 of the vacuum IG unit is typically evacuated down to a pressure below 10−3 Torr, and most preferably to a pressure below about 10−4 Torr of atmospheric pressure. Unfortunately, it typically takes twelve minutes or more in order to evacuate cavity 6 to such a low pressure. This lengthy period of time is sometimes undesirable, as it increases the time of production and ties up the operation of valuable capital-intensive machinery.
Thus, it will be appreciated by those skilled in the art that there is a need for techniques for evacuating a vacuum IG unit that takes less time.
An aspect of certain example embodiments relates to techniques for evacuating a thermally insulating panel such as a vacuum insulating glass (IG) unit, where it takes no more than twelve minutes to evacuate the internal cavity down to a pressure of about 5×10′ Torr or less.
Another aspect of certain example embodiments relates to techniques for igniting a plasma within the internal cavity of a thermally insulating panel (e.g., vacuum IG unit) during the evacuation process, in order to speed up and/or improve the process of evacuation.
Another aspect of certain example embodiments relates to injecting a gas (e.g., argon, nitrogen, oxygen, hydrogen, etc.) into the internal cavity of a thermally insulating panel, and thereafter inductively ignite a plasma within the cavity by at least partially ionizing the gas. It has been found that the ignition of this plasma results in a quicker and/or more efficient evacuation of the cavity. Moreover, it has been found that the ignition of such a plasma during the evacuation process results in a final vacuum IG unit that tends to be more stable upon exposure to ultraviolet (UV) light.
Still another aspect of certain example embodiments relates to techniques for igniting a plasma within the cavity of a thermally insulating panel during an evacuation process, by utilizing an electromagnetic wave generating coil located outside of the cavity.
Certain example embodiments provide a method of making a thermally insulating panel, the method comprising providing a plurality of spacers between first and second substrates in order to space the substrates from one another; forming a seal located at least partially between the substrates so as to seal off a space between the substrates; and causing a plasma to be present in at least a portion of the space between the substrates during a process of evacuating the space.
Certain example embodiments of this invention relate to a method of making a vacuum insulating glass (VIG) unit. A VIG unit subassembly is located in close relative proximity to an array of electrodes, with the array of electrodes being organized in a plurality of individually activatable plasma-generating elements that are spaced apart from one another. The VIG unit subassembly includes first and second substrates separated from one another by a plurality of support pillars and an edge seal, with a space being defined between the first and second substrates. Plasmas are caused to be present in at least portions of the space between the substrates by selectively activating the elements before and/or during a process of evacuating the space.
Certain example embodiments of this invention relate to a method of making a vacuum insulating glass (VIG) unit. A VIG unit subassembly is provided, with the VIG unit subassembly including first and second substrates separated from one another by a plurality of support pillars, as well as a pump-out port and an edge seal, wherein a space is defined between the first and second substrates. The VIG unit subassembly is positioned above and/or below a plurality of individually actuatable plasma-generating elements. The plasma-generating elements are selectively actuated so as to cause at least one plasma front to be propagated through the space.
Certain example embodiments of this invention relate to an apparatus in which an array of electrodes are organized in a plurality of individually activatable plasma-generating elements that are spaced apart from one another. A controller is configured to activate the elements in a preprogrammed order. A pump is configured to feed purging gas into, and evacuate air from, a cavity of a VIG unit subassembly fed into the apparatus, with the cavity being at least partially defined by first and second substrates and an edge seal of the VIG unit subassembly. The controller is further configured to cause plasmas to be present in at least portions of the space between the substrates by selectively activating the elements before and/or during evacuating of the space by the pump.
According to certain example embodiments, the elements may be sequentially activated based on the elements' respective distances from a pump-out port provided to the VIG unit subassembly, starting with the element that is farthest from the pump-out port. This sequential activation may be repeated one or more times, e.g., to cause one or more corresponding plasma waves or plasma fronts to propagate through the space towards the pump-out port. When plural plasma fronts are provided, they may be sequential or at substantially the same time (but in different areas of the cavity).
According to certain example embodiments, a gas may be pumped into the space and the plasmas may be ignited thereafter, e.g., so that said igniting causes the plasma to be ignited by at least partially ionizing gas in the space. The gas may include nitrogen, argon, oxygen, and/or the like.
According to certain example embodiments, the plasma-generating elements may be oriented relative to the VIG unit subassembly such that an acute angle is formed between edges of the elements closest to the pump-out port and an adjacent edge of the VIG unit subassembly to which the pump-out port is closest. According to certain example embodiments, the elements may be substantially uniformly spaced apart from one another.
According to certain example embodiments, the individually actuatable plasma-generating elements may be fixed in position relative to VIG unit subassembly.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.